Transmitter and receiver structures for near-field wireless power charging

ABSTRACT

A wireless charging system comprises (i) a transmitter structure comprising a first metallic core disposed in an opening of the transmitter structure and (ii) a receiver structure comprising a second metallic core disposed in an opening of the receiver structure. The transmitter structure is configured to carry one or more radio frequency (RF) signals to the first metallic core when the receiver structure is within a threshold distance from the transmitter structure. In addition, the receiver structure is configured to be excited by the one or more RF signals from the transmitter structure, whereby the one or more RF signals are transferred from the first metallic core to the second metallic core when the transmitter structure and the receiver structure are within the threshold distance from each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is a continuation of U.S. patentapplication Ser. No. 15/046,026, entitled “Antenna Having CoaxialStructure for Near Field Wireless Power Charging,” filed Feb. 17, 2016(now U.S. Pat. No. 10,256,657), which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/387,206, entitled “Antennafor Near Field Wireless Power Charging,” filed Dec. 24, 2015, each ofwhich is incorporated by reference herein in its entirety.

TECHNICAL FIELD

This application generally relates to wireless charging system, and moreparticularly this application relates to hardware and softwarecomponents of the system.

BACKGROUND

Electronic devices, such as laptop computers, smartphones, portablegaming devices, tablets, or others, require power to operate. Asgenerally understood, electronic equipment is often charged at leastonce a day, or in high-use or power-hungry electronic devices, more thanonce a day. Such activity may be tedious and may present a burden tosome users. For example, a user may be required to carry chargers incase his electronic equipment is lacking power. In addition, some usershave to find available power sources to connect to, which is timeconsuming. Lastly, some users must plug into a wall or some other powersupply to be able to charge their electronic device. However, suchactivity may render electronic devices inoperable or not portable duringcharging.

Several attempts have been made to wirelessly transmit energy toelectronic devices, where a receiver device can consume the transmissionand convert it to electrical energy. However, most conventionaltechniques employ antennas that are unable to effectively work when adevice to be charged and a wireless charger are placed at very smalldistance from each other. For example, conventional solutions may employa transmitter and a receiver. The transmitter comprises antennas thatare configured to radiate electromagnetic waves with a power that is afunction of its electric feed signal's power and frequency. The receivercomprises antenna(s) that are configured to receive the power signalstransmitted by the transmitter. However, when the transmitter antenna(s)and the receiver antenna(s) are placed too close to each other, theantennas may detune as a result of coupling. During the transmissionphase, the tuning is then necessary in order to prevent an unwantedinjection of strong currents that could be generated in the receptionantenna by a received transmission signal. The unwanted reception of thetransmission signal in the reception antenna can only be prevented withthe use of the tuning circuit, and it adds to overall cost of thepackage.

Therefore, there is a need in the art to addresses the above describeddrawbacks of the conventional antenna based wireless charging systemsbeing employed to charge electronic devices.

SUMMARY

Wireless power systems disclosed herein attempt to address the abovedrawbacks and may provide a number of other features, as well. Wirelesspower system described herein provide coaxial structures that are usedin order to charge the electronic devices, and thereby solve the abovedescribed drawbacks of antennas being employed in charging of electronicdevices by conventional wireless charging systems.

In one embodiment, a wireless charging system comprises a first coaxialstructure configured to carry an RF signal present on a conductor; and asecond coaxial structure configured to be excited by an RF signal fromthe first coaxial structure, power being transferred from the firstcoaxial structure to the second coaxial structure when the first coaxialstructure and the second coaxial structure are placed in proximity toeach other.

In another embodiment, a method for charging an electronic device in awireless charging system comprises upon a first planar coaxial structurebeing proximately positioned to a second planar coaxial structure,exciting the first planar coaxial structure to allow for the transfer ofpower from the first planar coaxial structure to the second planarcoaxial structure.

In yet another embodiment, a wireless charging system comprises a secondcoaxial structure configured to be excited by an RF signal, whereinpower is transferred from a first coaxial structure having an RF signalpresent to the second coaxial structure when the first coaxial structureand the second coaxial structure are placed in proximity to each other.

In another embodiment, a wireless charging system comprises a firstcoaxial structure carrying an RF signal, power is transferred from thefirst coaxial structure to a second coaxial structure when the firstcoaxial structure and the second coaxial structure are excited inproximity to each other.

Additional features and advantages of an embodiment will be set forth inthe description which follows, and in part will be apparent from thedescription. The objectives and other advantages of the invention willbe realized and attained by the structure particularly pointed out inthe exemplary embodiments in the written description and claims hereofas well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings constitute a part of this specification andillustrate embodiments of the invention. The present disclosure can bebetter understood by referring to the following figures. The componentsin the figures are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of the disclosure.

FIG. 1A is a schematic diagram of a front view of a first coaxialstructure, in accordance with an embodiment of the present disclosure.

FIG. 1B is a schematic diagram of a rear view of a first coaxialstructure, in accordance with an embodiment of the present disclosure.

FIG. 2A is a schematic diagram of a front view of a second coaxialstructure, in accordance with an embodiment of the present disclosure.

FIG. 2B is a schematic diagram of a rear view of a second coaxialstructure, in accordance with an embodiment of the present disclosure.

FIG. 3A is an illustration of showing a coaxial structure on atransmitter side.

FIG. 3B is a schematic diagram showing a first coaxial structure and asecond coaxial structure, in accordance with an embodiment of thepresent disclosure.

FIG. 4 is a schematic diagram showing an electronic device, inaccordance with an embodiment of the present disclosure.

FIG. 5 is a flow diagram illustrating operation of charging of anelectronic device in accordance with one or more embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Reference will now be made to the exemplary embodiments illustrated inthe drawings, where specific language will be used here to describe thesame. It should be understood that no limitation of the scope of theinvention is intended by the descriptions of such exemplary embodiments.Alterations and further modifications of the exemplary embodiments andadditional applications implementing the principles of the inventivefeatures, which would occur to a person skilled in the relevant art andhaving possession of this disclosure, are to be considered within thescope of this disclosure.

Electronic devices, especially wearable devices, have to be chargedregularly. Wireless charging simplifies the charging process. A chargermay include a power generator, and the electronic device may include areceiver for receiving a transfer of wireless energy. Each of the powergenerator and receiver may include a coaxial structure that provides forthe wireless transfer of energy, as described herein. As a summary, whenthe receiver coaxial structure is not near the transmitter coaxialstructure, input impedance of the transmitter coaxial structure is akinto open circuit, therefore, power is not leaked out of the transmittercoaxial structure. Power transfer happens when the receiver coaxialstructure is placed near the transmitter coaxial structure and thereceiver coaxial structure is excited with the same RF fielddistribution (mode) as the transmitter coaxial structure.

FIG. 1A and 1B is a schematic diagram of a front view and a rear viewrespectively of a first coaxial structure 100, in accordance with anembodiment of the present disclosure. In one embodiment, the firstcoaxial structure 100 may be part of a charging device. In anotherembodiment, the first coaxial structure 100 may correspond to or beassociated with a charging device. In either case, the first coaxialstructure 100 may be in electrical communication with a charging device.As shown, the first coaxial structure 100 is square, and includes atransmission line (TL) that produces a transmission-line RF field from atransmitter (i.e., coaxial mode), as further described in FIG. 3A. Theshape of the first coaxial structure 100 may alternatively berectangular, circular, or any other geometric or non-geometric shape.

The first coaxial structure 100 may include a housing defined by aplurality of sidewalls 102, a top surface 104, and a bottom surface 106.The top surface 104 extends over the bottom surface 106. The sidewalls102 span between the top surface 104 and the bottom surface 106. The topsurface may include vias, as shown, or not include vias. In someembodiments, the housing is formed of plastic, but alternatively oradditionally can be formed of other materials, such as wood, metal,rubber, glass, or other material that is capable of providing for thefunctionality described herein. As illustrated in FIG. 1A and 1B, thefirst coaxial structure 100 has a square shape, but othertwo-dimensional or three-dimensional shapes are possible, such as acube, a sphere, a hemisphere, a dome, a cone, a pyramid, or any otherpolygonal or non-polygonal shape, whether having an open-shape or aclosed-shape. In some embodiments, the housing of the first coaxialstructure 100 is waterproof or water-resistant.

The first coaxial structure 100 may be stiff or flexible and optionallyinclude a non-skid bottom surface to resist movement. Similarly, the topsurface 104 may be or include non-skid region(s) or be entirely non-skidto resist motion between the top surface 104 and an electronic device.Still yet, a bracket or other guide may be mounted to the top surface104 to assist a user with positioning of an electronic device. Thehousing may contain various components of the first coaxial structure100.

The first coaxial structure 100 may include a substrate 108. Thesubstrate may include metamaterials, or traditional materials such asFR4 or any other material known in the art. The metamaterials of thepresent disclosure may be a broad class of synthetic materials that areengineered to yield permittivity and permeability characteristicscompliant with the wireless charging system requirements. Themetamaterials described herein radiate on their own, and act as verythin reflectors.

The first coaxial structure 100 may be configured to keep desiredcurrents inside and undesired current outside and thereby retaining theelectric current in the first coaxial structure 100. In the exemplaryembodiment, the electric current is an RF signal that is carried on thefirst coaxial structure 100. The first coaxial structure 100 may furtherinclude a core 110. The core 110 is formed at a center of the substrate108. In one embodiment, the core 110 is made up of metal to operate asan electrical conductor, as understood in the art. In anotherembodiment, the core 110 may be made of any suitable material known inthe art without moving out from the scope of the present disclosure.

The first coaxial structure 100 may further include coaxial connector112 having two ends where one end of the coaxial connector 112 mayextend from the bottom surface 106 and the other end of coaxialconnector 112 is connected to a ground terminal.

FIG. 2A and 2B is a schematic diagram of a front view and a rear viewrespectively of a second coaxial structure 200, in accordance with anembodiment of the present disclosure. In one embodiment, the secondcoaxial structure 200 may be part of an electronic device, such as amobile telephone, comprising a battery. In another embodiment, thesecond coaxial structure 200 may be part of a portable battery device.In yet another embodiment, the second coaxial structure 200 may beattached to an electronic device, such as wearable watch comprising abattery.

The second coaxial structure 200 may include a housing defined by aplurality of sidewalls 202, a top surface 204, and a bottom surface 206.The top surface 204 extends over the bottom surface 206. The sidewalls202 span between the top surface 204 and the bottom surface 206. In someembodiments, the housing is formed of plastic, but alternatively oradditionally can be formed of other materials, such as wood, metal,rubber, glass, or other material that is capable of providing for thefunctionality described herein. As illustrated in FIG. 2A and 2B, thesecond coaxial structure 200 has a square shape, but othertwo-dimensional or three-dimensional shapes are possible, such as acube, a sphere, a hemisphere, a dome, a cone, a pyramid, or any otherpolygonal or non-polygonal shape, whether having an open-shape or aclosed-shape. In some embodiments, the housing of the second coaxialstructure 200 is waterproof or water-resistant.

The second coaxial structure 200 may be stiff or flexible and optionallyinclude a non-skid bottom surface to resist movement. Similarly, the topsurface 204 may be or include non-skid region(s) or be entirely non-skidto resist motion between the top surface 204 and an electronic device.Still yet, a bracket or other guide may be mounted to the top surface204 to assist a user with positioning of an electronic device. Thehousing may contain various components of the second coaxial structure200.

The second coaxial structure 200 may include a substrate 208. Thesubstrate may include metamaterials, or traditional materials such asFR4 or any other material known in the art. The metamaterials of thepresent disclosure may be a broad class of synthetic materials that areengineered to yield permittivity and permeability characteristicscompliant with the wireless charging system requirements. Themetamaterials described herein radiate on their own, and act as verythin reflectors.

The second coaxial structure 200 may be configured to keep desiredcurrents inside and undesired current outside and thereby retaining theelectric current in the second coaxial structure 200. In the exemplaryembodiment, the electric current is an RF signal that is carried on thesecond coaxial structure 200. The second coaxial structure 200 mayfurther include a core 210. The core 210 is formed at a center of thesubstrate 208. In one embodiment, the core 210 is made up of metal tooperate as an electrical conductor, as understood in the art. In anotherembodiment, the core 210 may be made of any suitable material known inthe art without moving out from the scope of the present disclosure.

The second coaxial structure 200 may further include circuitry 212, suchas a transducer device, to convert coaxial field radiation into energyto power or charge a battery of the electronic device.

FIG. 3A is an illustration of showing a coaxial structure 302 on atransmitter side. The coaxial structure 302 is shown to include asidewall with a copper surface 304, conductor 306, and substrate 308.The substrate may be a conventional substrate or otherwise. When thecoaxial structure 302 is excited, an RF field distribution (mode) 310occurs in the substrate 308 between the sidewall with copper surface 304and conductor 306. Size of the coaxial structure 302 may be scaled up ordown without limit. The coaxial structures 302 and 312 may be identicaland reciprocal in structure or be different in structure but becomplementary in that the two coaxial structures 302 and 312 are able toconnect or otherwise be arranged such that the RF field distribution 310is generated based on the coaxial structures 302 and 312 being near toone another. In one embodiment, especially if the coaxial structures 302and 312 are small, magnet(s) may be integrated or attached to either orboth of the coaxial structures 302 and 312 to help alignment andpositioning to maintain the coaxial structures 302 and 312 being near toone another.

In operation, when a coaxial structure 312 on the receiver side (seeFIG. 3B) is not positioned near the coaxial structure 302 of thetransmitter side, as shown in FIG. 3A, the input impedance of thetransmitter unit is akin to an open circuit (that is, the inputimpedance is infinite) and the receiver unit is not excited with thesame RF field distribution (mode) so power is not leaked or otherwisetransferred from the coaxial structure 302. However, when the coaxialstructure 312 on a receiver side is positioned near the coaxialstructure 302, as shown in FIG. 3B, the receiver unit is excited withthe same RF field distribution (mode).

FIG. 3B is a schematic diagram showing the first coaxial structure 302of a transmitter and the second coaxial structure 312 of a receiver, inaccordance with an embodiment of the present disclosure. A more detailedconstruction of the first coaxial structure 302 is presented in FIGS. 1Aand 1B. A more detailed construction of the second coaxial structure 312is described in FIGS. 2A and 2B.

In illustrated embodiment, when the surfaces of the first coaxialstructure 302 and the second coaxial structure 312 are positioned at aproximate distance from each other, a coaxial field radiation may beexcited due to the presence of an electric current in each of the firstcoaxial structure 302 and the second coaxial structure 312. The coaxialfield radiation that is excited or otherwise generated results in adistribution of the coaxial field radiation in an area around the firstcoaxial structure 302 and the second coaxial structure 312, and transferof the current from the coaxial field radiation may be transferred fromthe first coaxial structure 302 to the second coaxial structure 312 forconversion by a receiver into power to charge a battery of an electronicdevice that is coupled to the second coaxial structure 312. In theillustrated embodiment, the proximate distance may be any distance thatis less than 10 mm, however it will be appreciated by a person havingordinary skill in the art that the proximate distance is not limited to10mm or less, and may be more than 10mm without moving out from thescope of the disclosed embodiments.

In another embodiment, when the surfaces of the first coaxial structure302 and the second coaxial structure 312 are touched to each other, acoaxial field radiation may be created due to the presence of electriccurrent in each of the first coaxial structure 302 and the secondcoaxial structure 312. The coaxial field radiation is then distributedin an area around the first coaxial structure 302 and the second coaxialstructure 312, and may be converted into power to charge a battery of anelectronic device that is coupled to the second coaxial structure 312.

In one embodiment, the surfaces of the first coaxial structure 302 andthe second coaxial structure 312 may comprises magnetic propertiesand/or configured with magnets that may pull the surfaces of the firstcoaxial structure 302 and the second coaxial structure 312 towards eachother such that the distance between the first coaxial structure 302 andthe second coaxial structure 312 is less than a proximate distance. Whenthe first coaxial structure 302 and the second coaxial structure 312 areproximately positioned, a coaxial field radiation may be generated dueto the presence of current in the first coaxial structure 302 and,optionally, the second coaxial structure 312. When both coaxialstructures 302 and 312 are in the same mode, as understood in the art,and placed in proximate position to one another, power transfers fromthe first coaxial structure 302 to the second coaxial structure 312. Inan alternative embodiment, a structure, such as top surfaces 104 and 204may have magnetic properties or be configured with magnets to provideattraction properties to bring and maintain the coaxial structures 302and 312 in proximity to one another. The coaxial field radiation 306 maythen be converted into power to charge a battery of an electronic deviceusing a suitable circuitry including a rectifier and a power converter.

FIG. 4 is a schematic diagram showing an electronic device 402, inaccordance with an embodiment of the present disclosure. An exemplaryelectronic device 402 may be positioned near a charging device 404. Theelectronic device 402 includes a second coaxial structure mounted on theelectronic device 402 for charging a battery in the electronic device402. The charging device 404 includes a first coaxial structure. A moredetailed construction of the first coaxial structure is described inFIG. 1A and 1B. A more detailed construction of the second coaxialstructure is described in FIG. 2A and 2B.

The electronic device 402 may include a second coaxial structure, aswell as a battery that is to be charged in accordance with the presentdisclosure. In some embodiments, the electronic device 402 comprisescircuitry including one or more switch elements, a rectifier, and apower converter, where the rectifier and power converter may becombined. In some embodiments, the second coaxial structure may comprisecircuitry including one or more switch elements, a rectifier, and apower converter, where the rectifier and power converter may becombined. The second coaxial structure may be positioned within theelectronic device 402 and connected to the battery.

The charging device 404 may include a second coaxial structure. When theelectronic device 402 and the charging device 404 are brought close toeach other such that the distance between the electronic device 402 andthe charging device 404 is less than the proximate distance, then acoaxial field radiation is generated due to the presence of electriccurrents at least the first and second coaxial structure.

The switch elements may be capable of detecting coaxial field, anddirecting the radiations to the rectifier when the detected radiationscorrespond to a power level that exceeds a threshold. For example, insome embodiments, the switch may direct the received coaxial field tothe rectifier when the coaxial radiations received is indicative of awireless power transfer greater than a pre-defined threshold limit. Inother embodiments, the switch may direct the received coaxial field whenthey are indicative of a wireless power transfer greater than apre-defined limit. This switching acts to protect from damagingelectronic components of the electronic device 402 by preventing a powersurge from being applied thereto.

The generated coaxial field is then converted to a power signal by apower conversion circuit, such as a rectifier circuit for charging abattery of the electronic device 402. In some embodiments, the totalpower output is less than or equal to 1 Watt to conform to FederalCommunications Commission (FCC) regulations part 15 (low-power,non-licensed first coaxial structures). In an embodiment, the rectifiermay include diodes, resistors, inductors, and/or capacitors to rectifyalternating current (AC) voltage generated to direct current (DC)voltage, as understood in the art. In some embodiments, the rectifierand switch may be placed as close as is technically possible to minimizelosses. After rectifying AC voltage, DC voltage may be regulated and/orconditioned using power converter. Power converter can be a DC-DCconverter, which may help provide a constant voltage output, regardlessof input, to an electronic device or, as in this embodiment, to abattery.

FIG. 5 is a flow diagram 500 illustrating operation of charging of anelectronic device in accordance with one or more embodiments of thepresent disclosure.

At step 502, an electronic device with a second coaxial structure may beplaced in proximity with a charging device. The second coaxial structuremay be positioned within or attached to the body of the electronicdevice. The second coaxial structure may be configured to keep desiredcurrents inside and undesired current outside and thereby maintaining anelectric current in the second coaxial structure.

The charging device may be provided with a first coaxial structure. Thefirst coaxial structure may be positioned within or attached to the bodyof the electronic device. The first coaxial structure may be configuredto keep desired currents inside and undesired current outside andthereby maintaining an electric current in the first coaxial structure.

At step 504, in response to the electronic device being positioned in aproximate distance to the charging device, power may be transferred fromthe charging device to the electronic device. In one embodiment, theproximate distance is less than about 10 mm. Other distances to bewithin a proximate distance are also possible. Upon a planar surface ofthe first coaxial structure being proximately positioned to a planarsurface of the second coaxial structure, the first planar coaxialstructure excites the same RF field distribution (mode) on the secondcoaxial structure to transfer a charge from the first coaxial structureto the second coaxial structure.

At step 506, the electronic device may be charged by converting thecoaxial field radiation into a suitable form of energy that is used topower the electronic device. The generated coaxial radiation may beconverted to a power signal by a power conversion circuit for examplerectifier circuit for charging a battery of the electronic device. Therectifier may include diodes, resistors, inductors, and/or capacitors torectify alternating current (AC) voltage generated to direct current(DC) voltage, as understood in the art. In some embodiments, the totalpower output is less than or equal to 1 Watt to conform to FederalCommunications Commission (FCC) regulations part 15 (low-power,non-licensed first coaxial structures).

The foregoing method descriptions and flow diagrams are provided merelyas illustrative examples and are not intended to require or imply thatthe steps of the various embodiments must be performed in the orderpresented. The steps in the foregoing embodiments may be performed inany order. Words such as “then,” “next,” etc., are not intended to limitthe order of the steps; these words are simply used to guide the readerthrough the description of the methods. Although process flow diagramsmay describe the operations as a sequential process, many of theoperations can be performed in parallel or concurrently. In addition,the order of the operations may be rearranged. A process may correspondto a method, a function, a procedure, a subroutine, a subprogram, etc.When a process corresponds to a function, its termination may correspondto a return of the function to the calling function or the mainfunction.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

The preceding description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the following claims and theprinciples and novel features disclosed herein.

While various aspects and embodiments have been disclosed, other aspectsand embodiments are contemplated. The various aspects and embodimentsdisclosed are for purposes of illustration and are not intended to belimiting, with the true scope and spirit being indicated by thefollowing claims.

1-2. (canceled)
 3. A transmitter structure for delivering wirelesspower, comprising: a housing; a metallic core disposed in an openingdefined by the housing; and one or more magnets, integrated with asurface of the housing, configured to magnetically attract one or moreother magnets integrated with a receiver structure in order to bring andmaintain the transmitter structure and the receiver structure within athreshold distance from each other, wherein: the transmitter structureis configured to carry one or more radio frequency (RF) signals to themetallic core when the receiver structure is within the thresholddistance from the transmitter structure, and the receiver structure isconfigured to receive and convert the one or more RF signals into usableenergy to power an electronic device coupled to the receiver structure.4. The transmitter structure of claim 3, wherein the housing isconfigured to keep desired currents inside the transmitter structure andundesired currents outside of the transmitter structure.
 5. Thetransmitter structure of claim 3, wherein the surface of the housingincludes one or more non-skid regions to resist motion of the receiverstructure when the receiver structure is within the threshold distancefrom the transmitter structure.
 6. The transmitter structure of claim 3,wherein the transmitter structure operates as an open circuit when thereceiver structure is not within the threshold distance from thetransmitter structure, such that wireless power does not leak from thetransmitter structure.
 7. The transmitter structure of claim 3, whereinthe surface of the housing is a planar surface configured to bepositioned adjacent to a planar surface of the receiver structure whenthe receiver structure is within the threshold distance from thetransmitter structure.
 8. The transmitter structure of claim 3, whereinthe housing comprises at least one metamaterial.
 9. The transmitterstructure of claim 3, wherein the metallic core is at a center locationof the housing.
 10. The transmitter structure of claim 3, wherein: thetransmitter structure is part of a charging device; and the housing isalso part of the charging device.
 11. The transmitter structure of claim3, further comprising a transmission line that feeds the one or more RFsignals.
 12. A wearable electronic device for receiving wireless power,comprising: a receiver structure, including: a housing; a metallic coredisposed in an opening defined by the housing; and one or more magnets,integrated with a surface of the housing, configured to magneticallyattract one or more other magnets integrated with a transmitterstructure in order to bring and maintain the transmitter structure andthe receiver structure within a threshold distance from each other,wherein: the transmitter structure is configured to transfer one or moreradio frequency (RF) signals to the metallic core when the receiverstructure is within the threshold distance from the transmitterstructure, and the receiver structure is configured to convert the oneor more RF signals into usable energy to power the wearable electronicdevice.
 13. The wearable electronic device of claim 12, wherein thewearable electronic device is a wearable watch.
 14. The wearableelectronic device of claim 12, further comprising a battery, whereinreceiver structure is further configured to convert the one or more RFsignals into usable energy to charge the battery.
 15. The wearableelectronic device of claim 12, further comprising one or more switchelements configured to (i) detect the one or more RF signals transferredby the transmitter structure, and (ii) direct the one or more RF signalsto conversion circuitry when a power level of the one or more RF signalsexceeds a threshold.
 16. The wearable electronic device of claim 15,wherein the one or more switch elements minimize power surges in thewearable electronic device, thereby protecting components of thewearable electronic device from power-surge related damage.
 17. Thewearable electronic device of claim 12, wherein the housing isconfigured to keep desired currents inside the receiver structure andundesired currents outside of the receiver structure.
 18. The wearableelectronic device of claim 12, wherein the threshold distance is lessthan 10 mm.
 19. The wearable electronic device of claim 12, wherein thereceiver structure is further configured to be excited by the one ormore RF signals transferred from the transmitter structure when thereceiver structure is within the threshold distance from the transmitterstructure.
 20. The wearable electronic device of claim 12, wherein thereceiver structure further comprises circuitry to convert the one ormore RF signals into usable energy to power the wearable electronicdevice.
 21. The wearable electronic device of claim 20, wherein thecircuitry includes a rectifier and a power converter.
 22. A wirelesscharging system comprising: a transmitter structure comprising: a firstmetallic core disposed in an opening of the transmitter structure; andone or more first magnets; and a receiver structure comprising: a secondmetallic core disposed in an opening of the receiver structure; and oneor more second magnets, wherein: the one or more first magnets areconfigured to magnetically attract the one or more second magnets inorder to bring and maintain the transmitter structure and the receiverstructure within a threshold distance from each other, the transmitterstructure is configured to transfer one or more radio frequency (RF)signals from the first metallic core to the second metallic core whenthe receiver structure is within the threshold distance from thetransmitter structure, and the receiver structure is configured toconvert the one or more RF signals into usable energy to power anelectronic device coupled to the receiver structure.